1. Field of the Invention
The present invention generally relates to a spool, and more specifically to a spool for a spinning reel to be attached to a non-circular portion formed on a tip of a spool shaft allowed to move back and force but prevented from rotating with respect to a reel unit.
2. Background Information
In a spinning reel, especially in a front-drag spinning reel, a non-circular portion is formed on a tip of a spool shaft for applying the drag force to a spool. More specifically, the non-circular portion includes parallely opposed sides. Regarding the front-drag spinning reel, the spool shaft is allowed to move back and forth with respect to a reel unit, but is prevented from rotating with respect to the reel unit. Also, the spool is capable of rotating with respect to the spool shaft. Additionally, the spool is configured to be braked by a drag mechanism when a fishing line is reeled out.
For example, Japanese Patent Application Publication No. JP-A-2000-139286 discloses a spool for the front-drag spinning reel. According to the publication, a ball bearing is arranged between a spool shaft and the spool for smoothing rotation of the spool in a line-releasing direction when the drag force is applied to the spool.
Also, the spool for the spinning reel conventionally includes a spool unit, a tubular member, and a pair of ball bearings. The tubular member is rotatably attached to a non-circular portion of the spool shaft. The ball bearings are attached to the tubular member through a predetermined space. The ball bearings also rotatably support the spool unit. Furthermore, the tubular member is prevented from rotating and moving back and forth with respect to the spool shaft by means of a screw member penetrating the non-circular portion of the spool shaft.
With the configuration, wobble does not easily occur between the spool shaft and the spool unit. Accordingly, the spool is capable of smoothly rotating when the drag force is applied to it.
According to the above-mentioned conventional configuration, the tubular member provided in the spool is prevented from rotating with respect to the spool shaft. Additionally, a pair of ball bearings is attached to the tubular member. Accordingly, the spool is capable of smoothly rotating when the drag force is applied to the spool. However, the spool needs the tubular member and the pair of ball bearings. Accordingly, the spool structure will be complicated. Furthermore, a ball bearing is generally an expensive part. Therefore, manufacturing cost of the spool will be increased with the pair of ball bearings.